Objectives: Licensure of acellular pertussis vaccines for infant use was dependent upon the evaluation of recently completed efficacy trials. Comprehensive understanding of diagnostic procedures used in these trials to diagnose Bordetella pertussis infection was necessary for reviewers to make informed decisions on licensure and recommendations for use. With increasing use of acellular pertussis vaccines in the US, adequate surveillance of the immunization program and evaluation of outbreaks will require improved and innovative diagnostic approaches for all age groups. These techniques must improve on the sensitivity and specificity of currently available methods. To increase knowledge of pertussis diagnosis and epidemiology, the Laboratory has initiated projects: a) To develop and improve laboratory procedures to diagnose infection with B. pertussis, b) To determine which diagnostic procedures have the highest sensitivity and specificity for pertussis diagnosis at the different stages of illness and ages of patients c) To apply these techniques to understand epidemiology of pertussis. FY98 Activities: 1. Published results from a collaborative study with US Navy to determine the prevalence of B. pertussis infection in Marine Corps trainees. Previously, infection was evaluated by culture, serology and by polymerase chain reaction (PCR) technology. No subjects were positive by culture or PCR; however, depending on definition, 1 to 17% of subjects met a serological case definition for pertussis. 2. Continued analysis of a follow-up study in which antibodies were measured on paired serum samples collected at the beginning and at the end of training from a randomly selected set of 140 trainees from the same installations as evaluated above. Additionally, a health-status questionnaire was completed at the conclusion of training. Antibodies were measured to determine normal pre-training antibody levels and the frequency of pertussis-antibody rises in this population. 3. Provided ongoing technical advice and support for CDC contract entitled: "Measurement of antibodies to three antigens of Bordetella pertussis." The goal of the study is to develop pertussis serodiagnostic assays that can be transferred to state and regional clinical laboratories.